Green Fabrication of Sulfonium‐Containing Bismuth Materials for High‐Sensitivity X‐Ray Detection

Abstract Organic–inorganic hybrid materials based on lead and bismuth have recently been proposed as novel X‐ and gamma‐ray detectors for medical imaging, non‐destructive testing, and security, due to their high atomic numbers and facile preparation compared to traditional materials like amorphous selenium and Cd(Zn)Te. However, challenges related to device operation, excessively high dark currents, and long‐term stability have delayed commercialization. Here, two novel semiconductors incorporating stable sulfonium cations are presented, [(CH 3 CH 2 ) 3 S] 6 Bi 8 I 30 and [(CH 3 CH 2 ) 3 S]AgBiI 5 , synthesized via solvent‐free ball milling and fabricated into dense polycrystalline pellets using cold isostatic compression, two techniques that can easily be upscaled, for X‐ray detection application. The fabricated detectors exhibit exceptional sensitivities (14 100–15 190 µC Gy air −1 cm −2 ) and low detection limits (90 nGy air s −1 for [(CH 3 CH 2 ) 3 S] 6 Bi 8 I 30 and 78 nGy air s −1 for [(CH 3 CH 2 ) 3 S]AgBiI 5 ), far surpassing current commercial detectors. Notably, they maintain performance after 9 months of ambient storage. The findings highlight [(CH 3 CH 2 ) 3 S] 6 Bi 8 I 30 and [(CH 3 CH 2 ) 3 S]AgBiI 5 as scalable, cost‐effective and highly stable alternatives to traditional semiconductor materials, offering great potential as X‐ray detectors in medical and security applications.